Spark generating circuit having a voltage doubler and solid state control components



Oct. 24, 1967 w. J. ROBERTS 3,349,284

1 SPARK GENERATING CIRCUIT HAVING A VOLTAGE DOUBLER AND SOLID STATE NTROL COMPONENTS Filed Fe 25, 1965 ayz i tml lB l2 IL l 1\ AC 22 |4 u i a M INVENTOR.

ATTORNEYS United States Patent Oflfice 3,349,284 SPARK GENERATING CIRCUIT HAVING A VOLT- AGE DOUBLER AND SOLID STATE CONTRQL COMPONENTS William J. Roberts, St. Clair, Miclr, assignor to Eitra Corporation, Toledo, Ghio, a corporation of New York Filed Feb. 25, 1965, Ser. No. 435,187 7 Claims. (Cl. 315--223) This invention relates to a spark generating circuit for ignition of fluids in fuel burning apparatuses. More specifically, this invention relates to an ignition circuit including solid state components and in which the electrical energy stored by a capacitor is discharged through the primary of a spark coil to generate a high voltage current in'the secondary which will cause a spark between a pair of conventional sparking points.

Ignition systems in which a capacitor is used to store electrical energy and is periodically discharged through the primary in the spark coil are well known in the prior art. Because the energy required to induce a suflicient spark in the secondary of the spark coil is fixed by external requirements such as the type of fluid to be ignited, and because the power for such ignition systems is preferably AC line current, the capacitor must be of a size to store sufiicient energy for discharge to the primary of the spark coil. Due to space and cost limitations, a simple circuit which increases the voltage impressed upon the primary of the spark coil is desirable to increase the energy available, thus reducing the size and cost of the capacitor. Because the energy stored within a capacitor is equal to /2CV a voltage doubler in Combination With a controlled rectifier for discharging the capacitor through the primary of the spark coil will greatly increase the energy available to the secondary of the spark coil and may be provided as a relatively low cost, reliable, and compact unit.

It is therefore an object of this invention to provide a fluid ignition system wherein energy available from a capacitor is increased by a voltage doubler and which includes a solid state device which periodically conducts to discharge the capacitor through the primary of a spark coil.

It is another object of this invention to provide a fluid ignition powered by alternating current and which utilizes a solid state controlled rectifier to periodically release energy from a capacitor to the primary of a spark coil.

Other objects of the invention will be apparent from the following detailed description of a preferred embodiment thereof, reference being made to the accompanying drawings, in which:

FIGURE 1 is a circuit diagram of a first preferred embodiment of this invention, schematically showing a pair of spark points S connected to the secondary of a spark coil;

FIGURE 2 is another preferred embodiment of this invention in which the control means associated with the control electrode of a solid state controlled rectifier is a pair of neon glow lamps; and

FIGURE 3 is a third preferred embodiment of this invention in which the means for controlling the discharge of the energy storage means is a four layer diode.

Referring to FIGURE 1, a pair of terminals and 11 are provided for connection to an external source of alternating current, which, as previously explained, may be house current. Connected across lines 12 and 13 which extend from the terminals 10 and 11 is a solid state controlled rectifier 14 with its anode to cathode circuit directly across lines 12 and 13 and its control electrode 15 connected to line 12 through an adjustable resistor 16. The diode 17 is connected across lines 12 and 13 in paral- 3,34%,234 Patented Oct. 24, 1967 lel to the solid state control rectifier 14 and oppositely biased thereto. A capacitor 18 is connected in the line 12 with one side directly connected to the anode of the controlled rectifier 14 and the top of the adjustable resistor 16. A spark coil or pulse transformer 19 with its primary 20 connected in the line 13 and its secondary 21 connected to the points S completes the igniter circuit of FIGURE 1.

The operation of the circuit of FIGURE 1 is as follows. Assuming that the peak value of the applied AC voltage at the terminals 10 and 11 is E volts, when the applied voltage is positive at terminal 11, the capacitor 18 charges to E volts through the diode 17. When the applied voltage becomes positive at the terminal 10, the diode 17 and the controlled rectifier 14 block the discharge of the capacitor 18, and the voltage across the controlled rectifier 14 increases to approximately the value of 2E volts.

Because the resistance between the control electrode or gate 15 of the controlled rectifier 14 and its cathode is practically zero, the voltage drop across the adjustable resistor 15 is very nearly equal to the voltage across the anode-to-cathode circuit of the controlled rectifier 14. The controlled rectifier 14 is such that it will not fire until the current into its gate 15, which may be adjusted by the adjustable resistor 16, is at a suitable value. When the current into the gate 15 reaches this value, the control rectifier 14 fires and the energy stored in capacitor 18 is discharged through the control rectifier 14 and the primary 2!) of the pulse transformer 19. AS soon as the current flow from the AC power source has reversed its direction, the control rectifier 14 stops conducting and energy is again stored in the capacitor 18, as previously explained.

It has been found that the above described circuit, when used in connection with fluid burning apparatuses such as gas driers and the like, will operate satisfactorily on 117-volt AC house current and that the components, such as the controlled rectifier 14 and the diode 17, are relatively inexpensive and require a bias characteristic of only double line voltage. Furthermore, the capacitor 18 may be of relatively small size, as previously explained.

FIGURE 2 is a second preferred embodiment of the igniter circuit in which the variable resistor 16 in FIG- URE 1 has been replaced with a pair of neon tubes 22. The neon tubes 22 are selected with characteristics such that their breakdown or conduction point is about 2E volts, or twice line voltage. When this point is reached, the flow of current through the neon tubes 22 at the gate 15 of the controlled rectifier 14 will trigger this device, which consequently discharges the capacitor 18 through the pulse transformer primary 20 as previously described. In the embodiments of both FIGURES 1 and 2, the controlled rectifier 14 is preferably a silicone controlled rectifier (SCR), as previously explained.

In FIGURE 3, the control electrode 14 and its gate control circuit are replaced with a four layer diode 23 having the characteristic that it will not conduct until the voltage pressed across its anode-cathode circuit is approximately 2E volts, or twice line voltage. Operation of the igniter circuit with the four layer diode 23 is in other respects identical to the operation of the circuits of FIGURES 1 and 2 and previously described.

Various modifications of the above described preferred embodiments of the invention will be apparent to those skilled in the art and it is to be understood that such modifications can be made without departing from the scope of the invention, if within the spirit and tenor of the accompanying claims.

What I claim is:

1. An igniter circuit for a fluid burning apparatus comprising, in combination, a pair of terminals for connection to a source of alternating current, a solid state controlled rectifier having an anode, cathode and control electrodes with the anode-cathode circuit connected across said terminals, a voltage doubling means including a capacitor operably connected to said anode, a spark generating means operably connected to said controlled rectifier whereby conduction of said controlled rectifier will energize said spark generating means, and a control means operably connected between said voltage doubler means and the control electrode of said controlled rectifier whereby said controlled rectifier will fire when the voltage drop across said control means is approximately twice the source voltage.

2. The igniter circuit of claim 1 in which said control means is a resistor.

3. The igniter circuit of claim 1 in which said control means is at least one neon glow lamp connected in series between said voltage doubler means and said control electrode. a l

4. The igniter circuit of claim 1 in which said controlled rectifier is a silicon controlled rectifier. V

5. An igniter circuit for a fluid burning apparatus, comprising, in combination, a pair of terminals for connection to a source of alternating current, a solid state controlled rectifier having an anode, cathode and control electrodes with the anode-cathode circuit connected across said terminals, a diode connected in parallel with said controlled rectifier and oppositely biased thereto, a spark generating means operably connected to said controlled rectifier 0 whereby conduction by said controlled rectifier will energize said spark generating-means, an energy storage device connected to the anode of said controlled rectifier and a nected to said four layer rectifier whereby conduction by References ited UNITED STATES PATENTS 3,297,889

FOREIGN PATENTS 1,302,526 7/1962. France. 970,553 9/1964 Great Britain.

JAMES w. LAWRENCE, Primary Examiner.

s. A. SCHNEEBERGER, Examiner.

'1/1967. Breskend 30748.5 

1. AN IGNITER CIRCUIT FOR A FLUID BURNING APPARATUS COMPRISING, IN COMBINATION, A PAIR OF TERMINALS FOR CONNECTION TO A SOURCE OF ALTERNATING CURRENT, A SOLID STATE CONTROLLED RECTIFIER HAVING AN ANODE, CATHODE AND CONTROL ELECTRODES WITH THE ANODE-CATHODE CIRCUIT CONNECTED ACROSS SAID TERMINALS, A VOLTAGE DOUBLING MEANS INCLUDING A CAPACITOR OPERABLY CONNECTED TO SAID ANODE, A SPARK GENERATING MEANS OPERABLY CONNECTED TO SAID CONTROLLED RECTIFIER WHEREBY CONDUCTION OF SAID CONTROLLED RECTIFIER WILL ENERGIZE SAID SPARK GENERATING MEANS, AND A CONTROL MEANS OPERABLY CONNECTED BETWEEN SAID VOLTAGE DOUBLES MEANS AND THE CONTROL ELECTRODE OF SAID CONTROLLED RECTIFIER WHEREBY SAID CONTROLLED RECTIFIER WILL FIRE WHEN THE VOLTAGE DROP ACROSS SAID CONTROL MEANS IS APPROXIMATELY TWICE THE SOURCE VOLTAGE. 